1. Field of the invention.
The present invention relates to small transaxles such as used in riding lawn mowers and the like, and, more particularly, to horizontally oriented transaxles with vertical input shafts.
2. Description of the related art.
Manually shifted transaxles of the type concerned herein typically employ a shift shaft carrying a plurality of freely journalled speed change gears which can be selectively coupled to the shift shaft by a shift mechanism. Each of the speed change gears is in constant running mesh with one of a plurality of companion gears affixed to a counter shaft which rotate together in unison. The vertical input shaft transmits the input power to the transaxle via a bevel pinion gear engaged with a bevel gear freely rotatable on the shift shaft which has a combination gear enmeshed with a gear affixed to the counter shaft. The receiving bevel gear thereby drives the counter shaft which transfers the motion to the shift shaft via the selected speed change gear. The shift shaft then transmits the input power to the output axle shafts via a differential.
It is known in the art to provide a transaxle having a plurality of shafts disposed therein, including a vertical input shaft and axle shafts, which are disposed in a generally parallel relationship to each other. The vertical input shaft is operably connected to the axle shafts by transmission shafts which through gearing transmit rotational motion from the upper most input receiving shaft to the lower axle shafts. Moreover, the vertical input shaft is attached at the upper end thereof to a pulley, and is rotatably carried at the lower end thereof by a bearing formed in the housing of the transaxle. Because of the vertical height of the pulley and its associated input receiving shaft, such transaxles tend to have a relatively high profile height.
In certain applications, it is desireable to provide a transaxle having a relatively low profile height. The shafts within such a transaxle are typically oriented in a horizontal relationship to each other within the transaxle housing. For example, U.S. Pat. No. 4,966,574 to von Kaler, et al., assigned to the assignee of the present invention and incorporated herein by reference, discloses a horizontally oriented transaxle in which a shift shaft, counter shaft and output drive shafts are disposed in a common horizontal plane. Such a transaxle has the advantage of simplifying assembly and repair because of the ease of access to the shafts which are supported along the split line of the transaxle.
In applications such as riding lawnmowers, the vertical distance between the axle shafts and other components of the lawnmower may be relatively small. In some specific arrangements of riding lawn mowers, that vertical distance may be critical to the riding lawnmower design in order to provide space for other components. For these arrangements, it is thus desireable to provide a transaxle having a relatively low profile.
What is needed in the art is a horizontally oriented transaxle having an input shaft which receives rotational input power at a height which is closer to the axis of the axles than heretofore possible, thereby providing a transaxle with a lower profile.